Think of it like this: Arrowhead, the developers, spent almost 8 years developing the game, getting funding throughout from Sony, which managed the publishing side of things so they could focus on game development.

Then, around 6 months before release, over 7 years of development up to that point, Sony wanted PSN to be required for the game, and clearly by release time, that was not enough time to even implement or test that well enough.

Their hands were tied years in advance, they couldn't just let almost 8 years of their development time go to waste over one decision by their publisher, nor could they reasonably go against the publisher or get a new publisher only about 6 months before release.

On their end, they didn't do anything particularly wrong, unless they could see the future over 7 years before and realize Sony was going to practically pull the rug out from under them with everything in Sony's favor, a decision only actually made far more recently.